1. Field of the Invention
This invention relates to the preparation of vinylene fluorides by reaction of an N,N-disubstitutedaminosulfur trifluoride with a ketone preferably in the presence of a polar solvent and/or polar catalyst.
2. Prior Art
Vinylene fluorides, i.e. compounds having the group&gt;C.dbd.CF--, are an interesting class of compounds and their preparation by a direct process would be desirable. They have not been reported as obtainable from sulfur fluorides and organic carbonyl compounds. A few such compounds that have been prepared by other methods, e.g., 5-fluorouracil and Floxuridine [1-(2-deoxy-.beta.-D-ribofuranosyl)-5-fluorouracil], exhibit potent clinical activity. A method whereby vinylene fluorides could be readily obtained should lead to compounds having unusual chemical and pharmacological properties.
Organic compounds having a carbonyl group have been reacted with fluorinating agents such as sulfur tetrafluoride or an N,N-disubstitutedaminosulfur trifluoride to give the corresponding difluoride [Middleton, J. Org. Chem., 40, 574 (1975); U.S. Pat. Nos. 3,914,265 and 3,976,691 to Middleton; and Markovskij et al., Synthesis, 787 (1973)]. The reaction can be conducted in glass at ordinary pressure and temperature rather than in alloy pressure vessels resistant to corrosion when SF.sub.4 is used. In general, the reactions with carbonyl containing compounds and an aminosulfur trifluoride have been conducted in an inert polar or nonpolar solvent.
A few steroid compounds that have a ring fused in a position which is alpha to a ketone group have been reacted with SF.sub.4 and the resulting gem difluoride treated with an activated alumina to produce the corresponding vinylene fluoride (see U.S. Pat. No. 3,413,321 to Boswell) as in the equation ##STR1## 1-Fluorocycloalkenes have also been prepared by this procedure [Strobach and Boswell, J. Org. Chem. 36, 818 (1971)].